Economic Impact of Venous Thromboembolism After Hip and Knee Arthroplasty

Potential Impact of Rivaroxaban

Richard J Friedman; Nishan Sengupta; Michael Lees

Disclosures

Expert Rev Pharmacoeconomics Outcomes Res. 2011;11(3):299-306. 

In This Article

Discussion

Extrapolating the results from the economic model described here to the number of THAs and TKAs performed annually, even based on data from 2005, indicates that very considerable cost savings could be made by replacing enoxaparin with rivaroxaban for thromboprophylaxis after surgery. In addition, based on the efficacy of rivaroxaban compared with enoxaparin, the number of post-surgical symptomatic events would be reduced by over 10,000 per year, reducing the burden of post-surgical VTE.

The use of anticoagulants is inevitably associated with an increase in the risk of bleeding, which will have cost implications. The model included costs associated with major bleeding and, when the results of the model were appraised by the National Institute for Health and Clinical Excellence in the UK, the Evidence Review Group commented that "reporting and interpretation of the safety data were good and concluded that the manufacturer's submission appeared to contain an unbiased estimate of the effectiveness of rivaroxaban in relation to the main competitor, enoxaparin."

The costs associated with home nursing visits for prophylaxis after hospital discharge will be substantial if the predicted rise in THA and TKA by 2030 occurs – approximately half a million hip operations multiplied by US$100 each would be a considerable cost burden on the US healthcare budget. If guideline suggestions for extended thromboprophylaxis after knee operations are also adhered to, the increased costs using enoxaparin would be even larger.

The ACCP guidelines indicate that adjusted-dose vitamin K antagonists are one of the forms of thromboprophylaxis that should be used after THA or TKA.[3] Results from GLORY indicated that in the USA, 57% of THA and 39% of TKA patients received warfarin.[23] However, in contrast to enoxaparin, warfarin prophylaxis was decreased around the time of hospital discharge.[19] Not only does warfarin have many characteristics that make its use problematic,[60] but routine coagulation monitoring is also required to ensure patients remain within the recommended therapeutic range, at estimated costs of US$51.25 per patient per month in 2000.[61] In addition, warfarin is less effective than enoxaparin. After THA, a study found that during hospitalization, 0.3% of patients who received enoxaparin had VTE compared with 1.1% of those who received warfarin (p < 0.01).[62] Economic studies have also found that enoxaparin is a more cost-effective regimen for thromboprophylaxis than warfarin after THA.[40,63,64] Consequently, the use of rivaroxaban should also be substantially more cost effective than the use of warfarin after THA or TKA.

A limitation of the economic models discussed in this manuscript was the conservative approach adopted, which may poorly reflect actual costs. However, the baseline assumption was that only statistically significant differences were included, but when all nominal differences were included – in either direction – the results showed an even greater cost saving with rivaroxaban.

A recent paper has reported the results of an indirect comparison of rivaroxaban and the direct thrombin inhibitor dabigatran.[65] The authors conducted meta-analyses to obtain pooled treatment effects of each drug compared with enoxaparin. They stated that they could not compare rivaroxaban and dabigatran for efficacy events or bleeding rates because adjudication was performed by different committees. They concluded that their analysis suggested that the clinical data did not allow claims of one drug being superior to the other.

An even more recent article using an adjusted indirect comparison of a large number of trials concluded that rivaroxaban was superior to dabigatran in preventing VTE, but with a slight trend towards an increased rate of bleeding events.[66]

In addition to cost savings, the use of an oral, fixed-dose anticoagulant with no requirement for routine coagulation monitoring or dose adjustment should simplify thromboprophylaxis after THA and TKA and may improve compliance with guidelines for extended post-discharge thromboprophylaxis. This should further reduce the incidence and burden of VTE after THA and TKA.

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